Foldables: tempered glass is not an option on the inner display

A foldable's inner display has no cover glass the way a conventional phone does. It has a top layer of flexible polymer, far softer, and that softness is exactly what lets it fold tens of thousands of times. It also has one immediate consequence: it scratches very easily, a fingernail is enough.

Tempered glass is ruled out. Glass does not bend, however thin: on the inner panel it would crack at the first fold and, at worst, take the display's top layer with it. What does work is flexible film — TPU or hydrogel — which follows the movement of the crease.

Expect the central crease to leave a ridge, too. No film removes it, and many begin to lift there with use. It is almost always the point where they fail.

Foldables ship with an inner protector already applied. It is not a shipping film, however much it looks like one, and it is not designed to be removed: it is part of the panel's construction. Samsung states explicitly that users should not remove it and that replacement is a service-centre job.

If it lifts at an edge or gets scratched, the correct route is the service centre, not a fingernail. Peeling it off at home is the most common cause of permanent bubbles and damage to the inner panel — and it is damage a warranty is unlikely to cover, because it is attributed to use.

The outer display is conventional rigid glass and is protected like any phone: tempered glass for the exact model. It is genuinely worth doing, because that is the screen left exposed when the phone sits folded in a pocket alongside keys.

Two checks before buying. First, on the Flip models the cover screen shares its surface with the camera lenses, so the cutout has to be model-specific — a Flip 5 protector will not sit correctly on a Flip 6. Second, the protector must not stand proud of the frame, or the phone will not close fully and that loads the hinge.

• Exact model and generation: dimensions change between generations even when the name barely does.
• Material by display: flexible (TPU/hydrogel) inside, tempered glass outside. Never the reverse.
• The crease zone: look for films advertising reinforced adhesive down the middle, because that is where they lift.
• Thickness when closed: if the phone will not close flat, the protector is surplus or misaligned.
• Dust in the hinge: fit it in a bathroom after a shower, with damp air and no dust in suspension.

Prices change daily, so the price and availability that count are always the ones shown on Amazon once you follow the link.